A fuel cell works like a battery but does not run down or need recharging so long as the fuel is continually fed to the cell. In a direct methanol fuel cell (DMFC), methanol is used as a fuel, which is put in on one side of the fuel cell while air circulates on the other side. The two sides are separated by a membrane electrode assembly (MEA), which has a proton exchange membrane (PEM) sandwiched between two electrodes. As shown in FIG. 1, a fuel cell 120 includes an anode side 121 where a mixture of methanol (MeOH) and water (H2O) (also referred to as liquid methanol) is circulated around the anode (−). On the cathode side 122, air is circulated around the cathode (+). Through catalytic activation at the MEA, hydrogen atoms from the liquid methanol separate into protons (H+) and electrons (not shown). The electrons become the source of electricity provided by the fuel cell. Some of the protons migrate through to the membrane assembly to the cathode side 122, where they combine with oxygen and become water. While the byproduct of the spent fuel, CO2, on the anode side is easily vented out of the fuel cell, the byproduct, water, on the cathode side must be properly taken away.
A major advantage of fuel cells over rechargeable batteries is that fuel cells can generally operate for longer periods of time without recharging. Furthermore, “recharging” a fuel cell can be accomplished almost instantaneously by refueling with liquid methanol. In contrast, recharging a battery takes hours to complete.
Currently, the operating efficiency of direct methanol fuel cells, in general, is low, especially when the temperature of the fuel falls below a certain range. It is thus advantageous and desirable to increase the temperature of the fuel cell in order to improve the operating efficiency.